Delete them in the Developer Tools Simulator:

Now in Simulator choose the following in the navigation Hardware > Device > Manage Devices.

Then from the popup choose the Simulators tab and from the list of simulators just highlight the relevant simulator and press the delete button. You can also press the ctrl to get a popup menu when selecting the simulator.

Next delete the files on your drive:

First quit Xcode and go to the following directory.

/Users/[username]/Library/Caches/com.apple.dt.Xcode/Downloads/

And inside there you will find several dmg files, just delete the relevant simulator files such as com.apple.pkg.iPhoneSimulatorSDK11_3-11.dmg as an example.

Then go to the following directory.

/Library/Developer/CoreSimulator/Profiles/Runtimes/

Again choose the relevant simulator you want to delete such as iOS 8.1.simruntime for example.

Now restart Xcode and all the items will no longer be available plus you will have made a few gigabytes of space.

Note: If you forget and want to install them again choose the following Xcode > Preferences > Components tab.

me@grafxflow

I am a Full-stack Developer who also started delving into the world of UX/UI Design a few years back. I blog and tweet to hopefully share a little bit of knowledge that can help others around the web. Thanks for stopping by!